In recent years, problems due to electromagnetic noises are increasing in accordance with (i) reduction in size of electronic apparatuses in which electronic components are mounted, (ii) increase in operating speed of such electronic apparatuses, and (iii) diversification of such electronic apparatuses (such as wireless LAN and on-vehicle radar). For example, in an on-vehicle microcomputer or the like, the number of codes in software is more than 200,000 rows and an operating frequency reaches 100 MHz and, from those, problems of malfunctions of electronic circuits which are caused by electromagnetic noises generated by electronic components have become notable.
Moreover, a high frequency functional component (e.g., an amplifier, a phase shifter, an attenuator, or the like) which is mounted on an electronic apparatus has a problem that a property of the high frequency functional component changes due to electromagnetic coupling with an electromagnetic wave that is radiated from another high frequency radiation source. Furthermore, there is a problem that electromagnetic resistance itself of a semiconductor chip is decreasing due to reduction in size, finer wiring, reduction in power consumption, and the like.
Under the circumstances, it has become more important to provide an electronic component with a shield for blocking electromagnetic waves in order to protect the electronic component from external electromagnetic noises and to inhibit leakage of electromagnetic noises from the electronic component to the outside.
As a general structure of an electromagnetic shield for blocking such electromagnetic waves, there are structures as proposed in, for example, Patent Literature 1 and Patent Literature 2. As illustrated in (a) of FIG. 6, in an electronic device 100 proposed in Patent Literature 1, an electronic component 140 which is fixed to a printed circuit board 120 with solder 130 is covered with a case 110 and an electrically conductive circuit 121, the case 110 being an electrically conductive metal case or a resin case having a surface on which an electrically conductive layer is provided, and the electrically conductive circuit 121 being provided on the printed circuit board 120. As illustrated in (b) of FIG. 6, in an electronic device 200 proposed in Patent Literature 2, an electronic component 230 is covered with a metal case 210 and a metal substrate 220.